The soap component of personal washing products can, in general terms, comprise the soap of medium and/or long chain fatty acids. The soaps of medium chain length fatty acids, such a lauric acid, while being capable of producing a copious foam, can be harsh or aggressive in their reaction to skin, while the soaps of longer chain fatty acids, such as stearic acid, are generally mild, although lacking in their ability to produce adequate foam.
Non-soap detergents, particularly nonionic surfactants can confer mildness to personal washing products, but where rheological stability of such products is of paramount importance, particularly where a gel product is required, then stability problems can arise, such as lowering of viscosity during storage, unless careful attention is given to the choice of nonionic surfactants.
It is known to provide soap-based compositions containing ethoxylated alcohols in aerosol form, which will comprise more than one liquid phase, in contrast to the compositions of the invention which are single phase liquids. GB 1 423 179 (Wilkinson Sword), for example, relates to a pressurized shaving foam which comprises an emulsion of a foamable aqueous concentrate and a liquefied gaseous propellant. The aqueous concentrate may comprise from 2 to 12% by weight of soap and, from 1.5 to 15% by weight of ethoxylated fatty alcohols having 8-60 EO, and a substantial amount of water before emulsification with the propellant liquid.
Addition of low levels of soap to liquid detergents is known to inhibit foam formation. GB 1 487 256 (Henkel) relates to a liquid, lather-regulated washing and cleansing agent comprising a combination of ethoxylated alcohols and from 4 to 6% by weight of C.sub.12-18 fatty acid soap. Such levels of soap are said to inhibit the undesirable formation of lather in the compositions.
The present invention on the other hand relates to a stable detergent composition for personal washing, comprising a single liquid phase having desired rheological properties and a mild reaction to skin with adequate foaming which can be prepared by careful selection of both fatty acid soaps and ethoxylated fatty alcohols.